Recently, for reducing the processing time for silver halide photographic materials, a process of increasing the development speed by high temperature processing has been employed. "High temperature processing" generally means processing at a temperature higher than 30.degree. C., and the various problems of such a process are well known. In one of the problems, the increase of the development speed causes the increase of the formation of fog, the increase of the change in sensitivity and gradation, and the reduction of graininess and sharpness of images. In another one of the problems, the sensitivity and gradation largely change by the highly concentrated halogen ions (in particular, bromide ions) released and accumulated in a developer during development process, whereby a stable photographic property can not be obtained.
Various methods for overcoming these difficulties are known, but they are insufficient for eliminating these problems. For example, it is known to incorporate in a photographic material nitron as described in Japanese Patent Publication No. 28691/77 (corresponding to U.S. Pat. No. 3,915,710 and German Patent (OLS) No. 2,431,092) or an antifoggant such as 1-phenyl-5mercaptotetrazole, 5-nitrobenzotriazole, etc. However, nitron may have an antifogging action and a development restraining action but is very insufficient in the point of improving these actions and reducing reliance on the conditions of development. Also, the foregoing antifoggants have a high antifogging action, but the use of such an antifoggant greatly reduces sensitivity and does not improve the halogen reliance in developers.
Thus, silver halide photographic materials which can sufficiently endure severe development conditions required at present have not yet been obtained.